Soldiers snack on 3-year sandwich

LONDON, England --A sandwich that stays fresh for up to three years could be heading for supermarket shelves following a breakthrough by U.S. military scientists.

Experts at the U.S. Army Soldier Systems Center in Natick, Massachusetts, developed the "indestructible" sandwiches, which come in pepperoni and barbecue chicken flavour, to supplement battle rations, London-based New Scientist magazine said on Thursday.

The pocket-sized snacks -- tested and cautiously approved by American soldiers -- are designed to survive airdrops and extreme temperatures. They will keep for up to three years at 26C (79F), or for six months at 38C (100F) -- and are vacuum-sealed.

"The water activity of the different sandwich components needs to complement each other," project officer Michelle Richardson told New Scientist.

"If the water activity of the meat is too high you might get soggy bread."

The sandwiches come in laminated plastic pouches with an array of chemicals to seal the meat and inhibit bacterial growth.

Inspired by their breakthrough, the scientists are now experimenting with pizzas, bagels, burritos and even the staple peanut butter sandwich.

The culinary breakthrough is sure to filter down to grocery shelves. Dehydrated egg, freeze-dried coffee and processed cheese were all invented by the military and later became a part of civilian lives.

Senior research analyst Richard Perks, from London-based Mintel Retail Intelligence, predicts UK supermarkets would experiment with a long-lasting sandwich, for example one which would last for a few weeks:

He added: "But it would only find its way to the shelves if it was a cheap alternative. The trend is for customers to move away from products with additives."